Evaluation of Shear Wave Velocity Correlations and Development of New Correlation Using Cross-hole Data

Abstract

Seismic microzonation studies are being proposed in Pakistan. In addition, a downhole array of accelerometers was  planned to be installed in the University of Engineering and Technology, Mardan Campus. Therefore, extensive geotechnical and geophysical tests were conducted. Shear wave velocity (Vs) is a fundamental parameter required for these microzontation studies. It is feasible in terms of cost and space to determine Vs from Standard Penetration Test (SPT) or Cone Penetration Test (CPT) results through empirical correlations. The purpose of this paper is to explore the applicability and predictability of these correlations to the data collected from the area where downhole array is planned. Data from these surveys was used to evaluate relevant correlations selected from literature. Predicted shear wave velocity values from these correlations were compared with measured shear wave velocity values from seismic crosshole tests. Most SPT-Vs correlations evaluated showed low predictability. The SPT-Vs correlation that showed highest degree of fitness to the dataset was the one developed for Lucknow, India, a city with similar geological setting, workmanship and SPT method employed. Site specific SPT-Vs correlation was also proposed. Most of the CPT-Vs correlations evaluated showed considerable predictive capability compared to the SPT-Vs correlations.